Patent GB-1053770-A (GB)
IPC: G11C15/06
Abstract: 1,053,770. Superconductive circuits. GENERAL ELECTRIC CO. Sept. 20, 1963 [Sept. 27, 1962], No. 37185/63. Heading H3B. [Also in Divisions G4 and H1] An associative memory in which all words are interrogated simultaneously, signals a match in a flip-flop FF1, which flip-flops are interrogated sequentially until the first matched word is reached preventing further passage of the pulse until a selection flip-flops FF2 has permitted read-write operations on said matched word and reset the matched flip-flop FF1 to the non- matched condition in order that a further selection pulse may pass to the next matched word. Storage cell.-A clockwise circulating current represents a stored " 1 " and anticlockwise a " 0." To write a " 1 " a positive digit current is applied on digit line 101<SP>1</SP> and a current of unit magnitude on write line 102<SP>1</SP> through control of crystion 24<SP>1</SP> rendering it resistive and hence current I1 is of unit magnitude. The write current and then digit current is turned off which causes a negative current flow I2 and hence a circulating current of magnitude ¢I. To read a word, a word current on line 104<SP>1</SP> and a positive digit current on line 1011 is applied rendering cryotron 211 resistive and cryotron 22 resistive for a " 1," thus any voltage drop registering a " 1." To interrogate the cell a current flows through associative line 103<SP>1</SP> and a positive digit current for a " 1 " and a negative for a " 0 " is applied. Associative line 103<SP>1</SP> remains conducting for a match but a mismatch renders cryotron 23<SP>1</SP> resistive and current output is on shunt line 105<SP>1</SP>. Memory.-Storage cells are arranged in matrix formation and associated with each row representing a word is a match indicating flipflop FF1 and a selection flip-flop FF2 which is reset prior to each operation (current direction R) and an applied current on line 44 renders cryotrons 52 resistive to divert all word currents to associative lines 103<SP>1</SP> making cryotron 54 resistive and flip-flops FF1 in the set state (current direction S). A current applied on search line 45 makes cryotrons 56 resistive and digit switches 27 are positioned to represent an interrogation word, a match being indicated on associative line 103<SP>1</SP> and a mismatch on shunt line 105<SP>1 </SP>making cryotron 66 resistive and resetting flip-flop FF1. A select current is applied to line 58 and for a word mismatch, cryotron 60 is resistive and hence current continues on line 58 to interrogate the next flip-flop. For a word match, cryotron 61 is resistive and current is diverted to by-pass line 59 rendering cryotron 63 resistive and setting flip-flop FF2, the selection flip-flops FF2 of all subsequent rows remaining unselected. Cryotron 53 becomes superconductive and hence read and write operations may be performed on all word bits, the word current resetting match indicating flip-flop FF1 by rendering cryotron 64 resistive A second select pulse may be applied which will select the next matched row. When all rows have been selected in sequence the select current flows through the control of an " end " cryotron 65 to give a signal for a new operation.